Overload control for metal rolls.



G, OVBRLOAD GONTRQL EOE, META? Roms.

ZLFPLICATIOZI FILED JAH. 22, 1912.

FIG. i

GEORGE H. BLAXTER, OF BEAVER, PENNSYLVANIA.

OVERLOAD CONTROL Specification of Letters Patent.

FOR METAL ROLLS.

Parent-eu oet. 8,1912.

Application led January 22, 1912. Serial No. 672,620.

To all whom it may concern.'

Be it known that l, GEORGE H. BLAXTER. a subject of the King of Great Britain, and a resident of Beaver, in the county of Beaver and State or Pennsylvania, have invented a new and useful Improvement in Overload Control for Metal Rolls, of which the following is a specification.

This invention relates to means for controlling electric motor driven metal reducing rolls or other machines.

The object of the invention is to provide an arrangement whereby damage to the rolls or operating parts of the machine, or their driving' mechanism, is largely prevented l when the work sticks in the rolls or clogs the machine, or on account of excessive or dangerous overload from any'other cause.

The invntion comprises the construction and arrangement or parts hereinafter' de- I scribed and claimed.

ln the accompanying drawing Figure l is a view partly diagrammatic'ot the arrangement of apparatus,` the switch being shown TP 2 is a side view of in /ront elevation; i-lg.

the circuit breakerghand Fig. 3 is a cross sec-- l tion on the line 3 3, Fig. 2.

excessive or` dangerous overload.

The presentinventio'n may be used for cont-'rollingthe drive of any machine, the duty of which renders it peculiarly liable to ln the drawings however, l have shown the invention as applied for 4the control of the rolls of a metal reducing rolling mill. The rolls may be ot any character, but are represented'by 'rolls 3 such as are used in rolling plates or bars. These rolls are mounted in the usual housings and bearings` and aredriven from a suitable motor, that illustrated being an electric motor 5 suitably connected by a shaft and gearing to the necks of the rolls. ln conjunction with such rolls it is customary to usea ily wheel 6 usually placed in the'connection between the motor and the rolls, being shown as mounted upon shaft 7, which is in two sections 7, 7b, and forms 'part of such connection. 8 indicates the mains of the circuit for supplying current to motor 5.

@n the occurrence of excessive overloads with electric motor driven rolls it has been proposed to break the motor supply circuit. This, however,leaves the ily wheel connected to therolls with the result that the ,ily wheel produces more or less mischiei or damage.

ylll/lith@ my new arrangement l break the connection between the ily wheel and rolls, or broadly speaking, break the connection between the rolls and both the fly wheel and the motor. This mayv be variously accomplished, but as shown there is in the connection between the motor 5 and the rolls and particularly between the fly wheel and rolls, a magnetic coupling lO oi3 suitable form. Such magnetic couplings or friction clutches are well known, the same comprising an iron disk secured to one of the shaft sections Ta, and a corresponding disk secured to the other shaft member 7b, one or both ol which are provided with windings ll supplied by slip rings l2 in a branch or shunt circuit 18 from the main supply circuit 8. lt is per fectly obvious that as long as current is supplied to the windings of the coupling y'the two members thereof are attracted and, with the shaft sections, rotate in unison, but when the current to the winding or windings is interrupted the coupling becomes inactive and the sha-ft sections are free from each other.

lin the circuit of the magnetic coupling is located a circuit bre-alter of some convenient form arranged and designed. so as to open said branch circuit 13 in case or an overload on motor 5. Such overloadcircuit breakers are very well known. As shown, it comprises an actuating winding oresolenoid 16 in the main supply circuit 8 to motor o' and an, armature or core l? therefor controlling switch 18 in the branch circuit 13. The winding and armature' ofthe circuit breaker are so proportioned that upon normal-current to motor 5 the armature is not actuated, but upon -tlie occurrence of abnormal current to motor 5, such as occursuipon excessive overload, the armature or core is at tracted to open switch 18, thereby interrupting the ow of current to the magnetic coupling and releasing the rolls from the connection both of motor 5 of y wheel 6 by release of the shaft sections 7a, 7b from each other.

To prevent considerable flash and the danger of breaking down the insulation in the coils of the magnetic clutch l provide the particular :form of circuit breaker shown in detail in Figs. 2 and in connection with which is used a suitable non-inductive re sistance l5 in a branch or shunt circuit 19 across the clutch circuit 13.' The wires of this branch circuit 19 are led to contacts'QO on the bach of the wall panel or plate 2l, on

the forward t'ace of which is pivotally mounted the switch or circuit breaker 18 referred to. To close the contacts 20 a bridge 22 is provided mounted on the end of a rod 23 projecting through the panel and loosely engaged by the switch 18. A compression spring Q4 is placed between t-he headed end of rod 23 and the panel to constantly tend to close contacts 20. As shown the core or armature 17 is connected to a latch 25 which has a hooked end engaging a portion ot the switch 18 to hold the same closed. Upon rise in the current due to abnormal conditions the core 17 .lifts the latch 25 releasing the switch 18 to the act-ionof spring 241 which throws the swit'ch open and at the same time closes the contacts 2O by means of the bridge 22. A closed circuit is now established through the clutch coils and slip rings and the non-inductive resistance 15. 'llhe latter dissipates the shunt discharge and obviates the possibility oit sudden rise of potential which might injure the clutch coils. llhenthe switch 18 is again closed it engages rod 23, compresses spring 2t and opens contacts E20, the latch 25 again holding it in closed position.

The arrangement ple one tor protecting the rolls and the work 'therein-trom the evil eidects of an excessive overload, or from the edects ot the ily wheel in case thecircuit to the motor is broken. rlFhe articular arrangement shown in the drawlngs breaksthe connection to the roll between the ily wheel and the rolls. ln case the Hy wheel is on the opposite side of the rolls from the motor, a pair of magnetic couplings are necessary, one to disconnect the motor :trom the rolls and the other-to disconnect the Hy wheel from the rolls.

Various other arrangements of automatic means for ed'ecting the same results upon the occurrence oit excessive or dangerous overload will readily suggest themselves.

What lt claim is: 1. The combination of the operating parts of a machine, a motor tor driving the same, a ily wheel connected to said machine, connections trom said motor and 'dy wheel to said machine, and means controlled by the power supply of said motor and arranged to disconnect the ily wheel and motor from parts of a machine, oit an electric motor tor said machine on abnormal fluctuation in the power supply.

Q. The combination with the operating parts oit a machine, of a motor tor driving the same, a dy wheel connected to the machine, and means controlling the connections between the ily wheel and the machine and arranged to disconnect the tly wheel from the machine on variation in the power supply to the motoru 3. The combination with the operating `parts of a machine, of a motor for driving es the same, a tly wheel connected to said madescribed is a very sim-- annonce chine, a disconnectible coupling between the fly wheel and the' machine, and means controlled by theypower supply of said motor and arranged to disconnect said coupling on the occurrence of overload.

4. The combination with the operating parts of a machine, of a motor for driving the same, a ily wheel driven by said motor, a releasableconnection between said motor and the machine, and means controlled by the power supply of said motor 'for releasing the machine from the motor and dy wheel.

5. The combination with the operating parts of a machine, of a mot-or 'for driving the same, a ly wheel connected to said machine, connections from said motor and iiy wheel to said machine, and means controlling said connections and arranged to disconnect the ily wheel and motor from said machine on variation in the power supply to the motor.

6. rlhe combination with the operating parts of a machine, of: an electric motor for driving the same, a fly wheel connected lto said machine, connections from said motor and iiy wheel to said machine, and electrically controlled means arranged to disconnect the dy wheel and motor from said machine on occurrence of excessive or dan gerous overload.

7. rllhe combination with the operating parts of a machine, of an electric motor tor driving the same, a ly wheel connected to said machine, connections from said motor and fly wheel to said machine, and. a magnetic coupling in said connections arranged to disconnect the fly wheel andmotor 'trom the machine on an occurrence oit excessive or dangerous overload.

8. The combination with the .operating parts of a machine, ot an electric motor tor driving the same, a dy wheel 'connected to said machine, connections from said motor and Hywheel to said machine, a disconnectible coupling in said connections, an overload magnet in the motor circuit and connections whereby said magnet controls said coupling, said connections being arranged to disconnect the motor and tly wheel trom said machine on occurrencev of overload.

9. The combination with the operating actuating the same, a ily 'wheel connected to said machine, connections from said motor to said machine, a magnetic coupling in said connections, and an overload switch arranged in the circuitto the motor and con trolling the circuit to said coupling.

10. lThe combination with the Yoperating parts ot a machine, of an electric motor tor driving the same, connections between the said motor and machine including a -ily wheel, a disconnectible clutch in said connections between the dy wheel and the niarac I chine, movable means controlling said clutch, and an overload magnet in the motor circuit arranged to Control said movable means.

ll. The combination with the operating parts of a machine, of an electric motor having connections for driving the Same, a lywheel, connections from said y Wheel to said machine, a magnetic clutch in said connections, the clutch coils being in shunt to l the motor circuit, a switch in the clutch circuit, and a magnet in the motor circuit for cont-rolling said switch.

In testimony whereof, I have hereunto set my hand.

GEORGE H BLAXTER.

| Witnesses I T. J. CURLEY, N. P. ANDRE. 

